3. How do you draw up a control chart to apply statistical process control to a product's target value?

To create a control chart, follow the steps below.

• Confirm the target value to be aimed for during production. This target value is "often" set as the mid-point between the product's high and low tolerances. This target value should correspond to the average of the measured values. If this is not the case, the process is off-center and the necessary steps must be taken to bring the target value into line with the average.

• Calculate the standard deviation of the distribution of measured values of the product characteristic under MSP.

• Define a map on which the measured values of the value under MSP are shown on the ordinate and the time on the abscissa. Also shown on this map are the high and low values of the product tolerances, the target value and the +/-σ, +/-2σ, +/-3σ...